Cushion for keyboard cursor control stick

ABSTRACT

A cushion that can be attached to an existing cursor pointing device (control stick) on a computer or keyboard, or be integrally formed with the cap during manufacture. The cushion is flexible enough to prevent tissue damage to the user&#39;s fingers due to repetitive motions over an extended period of use, yet firm enough to transmit the desired pressure to the control stick. The cushion designed to be used on an existing control stick can be applied with an adhesive to a cap, or with a frictional fit directly to the control stick. The cushions are designed to be easily installed and replaced when worn.

BACKGROUND OF THE INVENTION

This invention relates in general to a computer input device, and inparticular to a cursor pointing device (cursor control stick), of anotebook-type portable computer or similar device.

A finger mouse or cursor control stick, as used in this application, isa man-machine interface device which controls the motion of a computerdisplay cursor. In particular, a control stick is a type of miniaturejoy stick which is intended to be operated by the tip of one finger ofthe user.

Typically, a control stick is mounted in a central location on acomputer keyboard, such as between the "G", "H" and "B" keys on astandard "QWERTY"-type keyboard. The control stick has a positionsensing mechanism which detects horizontal pressure in any horizontaldirection. The cursor moves in a direction that corresponds to thedirection of pressure exerted on the control stick and, in someembodiments, at a speed that corresponds to the amount of pressureexerted on the control stick. The control stick includes an elongatedshaft. The shaft of the control stick has a small diameter, thusallowing the control stick to be mounted between the keys of thecomputer keyboard without causing the placement of the keys to varygreatly from that expected by an experienced user. A cap is typicallyremovably mounted on the upper end of the control stick shaft, in orderto provide an enlarged contact surface for a user to press against onthe small diameter shaft of the control stick.

SUMMARY OF THE INVENTION

Some models of control sticks have a cap with a hard smooth surface,which became slippery during use from perspiration or a build-up ofnatural body oils. Thus a user has to press their finger with relativelygreat force against the cap to prevent their finger from slipping on thesurface of the cap. The need to press hard on the cap makes controldifficult, since the user cannot use the finesse and delicate movementstypically needed for rapid, accurate cursor movement. Also, pressinghard on the control stick is physically tiring to the finger, hand andforearm muscles of a user, and caused irritation, inflammation, andbruising of the finger tissue after a period of extended use.

A period of extended use, as used in this application, means a period ofuse of more than about one hour, and generally more than four hours andless than twelve hours. During such period of use, the user frequentlymanipulates the control stick. The frequency of manipulation of thecontrol stick during a representative task, such as word processing,will typically be at least every ten minutes, on average, and may bemuch more frequently, depending on the particular task and theparticular user.

Another type of a cap for a control stick has a textured outer surface.For example, one known control stick is equipped with a cap which isstippled with bumps which are about the same size and spacing as theabrasive on 150 grit sandpaper. While this approach may help prevent theslipping common with the earliest model cap, the textured cap is stillirritating to the finger of a user when used extensively, even with thelighter touch allowed by the textured surface. The uneven and relativelyhard surface of such caps still can cause inflamed tissue, bruising,soreness and finger fatigue in users which limits their ability tocomfortably use such a control stick for periods of extended use. Thepresent invention provides a "cushioned" cap for a control stick with asurface which provides the needed finger to cap friction to easily usethe control stick to move the cursor with a light touch, and which isformed of a relatively soft material so that the cap does not irritatethe body tissues of the user or result in finger fatigue, even afterperiods of extended use.

Various objects and advantages of this invention will become apparent tothose skilled in the art from the following detailed description of thepreferred embodiment, when read in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a typical portable computer employing acontrol stick having a cushioned cap in accordance with this invention.

FIG. 2 is a side view, partly in section, of the control stickillustrated in FIG. 1.

FIG. 3 is an enlarged sectional side view of the cap and the controlstick illustrated in FIGS. 1 and 2.

FIG. 4 is a side view of the cushioned cap illustrated in FIGS. 1through 3.

FIG. 5 is a sectional side view of a second embodiment of a cushionedcap in accordance with this disclosure.

FIG. 6 is a bottom plan view of the cap illustrated in FIG. 5.

FIG. 7 is a flowchart illustrating a method of manufacturing a controlstick in accordance with this disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, FIGS. 1 through 6 illustrate a firstembodiment of a control stick, indicated generally at 10, according tothis invention. The illustrated control stick 10 is a miniature joystick, such as the TrackPoint, TrackPoint II, or TrackPoint III controlsticks on notebook computers sold by the International Business MachinesCorporation. However, it will be appreciated, in light of the followingdisclosure, that the invention may be practiced on control devices otherthan such miniature joy sticks.

The control stick 10 is mounted in a keyboard 12 of a typicalnotebook-style microcomputer 14 having a pivotally mounted video screen15. The control stick 10 is mounted at a first end (not shown) to themicrocomputer 14, between the keys of the keyboard 12. A cap 18 isremovably mounted on the other end 21 of the control stick 10. Thecontrol stick 10 is usually made of a plastic material, and translatesthe pressure on the cap 18 into a command to move a cursor on a videodisplay of the computer 14.

The cap 18 of the control stick 10 is made of a relatively hardelastomeric material. At least a central portion of the outer surface 17of the cap 18 is provided with an attached cushion 20. The cushion 20can be made of any resilient material that can be attached to the outersurface 19 of the cap 18. Examples which may be suitable materialsinclude soft rubber, soft foam, and polyurethane foam. The preferredmaterial for the cushion 20 is polyurethane foam such as the type usedin expandable ear plugs. This type of foam product provides a surfacethat is relatively soft so as to not damage the tissues in the finger ofa user during periods of extended use.

Hardness can be characterized by measuring the force applied to a givenarea which is required to compress or deflect a material a givendistance. For example, a typical prior art cap, such as a cap suppliedwith the TrackPoint II control stick, is made of a relatively hardelastomeric material. During testing, a probe having a contact surfaceof approximately 1 mm² was pressed against such a cap to cause the probeto deflect the surface of the cap approximately 0.25 mm. A force ofapproximately 15 grams was required to compress the surface of the capinwardly this small amount. In contrast, one embodiment of the cushion20 of the present invention required a force of only 5 grams to beexerted by the probe to compress the surface of the cushion 20 the samedistance. According to the invention, a cushion 20 having a hardnesswhich would permit a probe having a contact surface of approximately 1mm² to deflect the surface of the cushion 20 by at least 0.25 mm whenurged by a force of 10 grams would generally be acceptable. Thepreferred embodiment of the invention has a hardness such that only 5grams of force is required to cause a probe having a contact surface of1 mm² to deflect the surface of the cushion 20 by at least 0.25 mm.

Preferably, the cushion 20 also provides a high coefficient of frictionwith the user's finger to permit easy positioning of the control stick10. The polyurethane foam of the cushion 20 is yielding to a degreedependent upon the thickness of the cushion 20. The thickness of thecushion 20 can easily be modified during manufacture to any desiredthickness.

Referring to FIG. 2, when the display 15 is folded down over thekeyboard 12 for storage, as is typical for most notebook computers, thedisplay 15 may contact the cushion 20. The cushion 20 is flattened asindicated by the phantom line 19, but will resiliently return to theposition indicated by the solid outline of the cushion 20. Theresiliency of the cushion 20 allows the cap 18 to have an enlargedcontact surface area and greater height above the keyboard 12 forincreased comfort of the user, without having to increase the spacingbetween the screen 15 and the keyboard 12. It will be appreciated bythose skilled in the art that the cushion 20 will preferably not be madefrom a material which would damage or stick to the display 15 if thedisplay 15 contacts the cushion 20.

Referring to FIGS. 3 and 4, the cushion 20 is, preferably, a disk ofmaterial having a generally semi-circular cross section. However, thecushion 20 may have any suitable shape, such as that of a flat-ended orhollow-ended cylinder. In the illustrated embodiment, the cushion 20 hasa convex end 22, and a second end 24. The convex end 22 is the contactsurface of the cushion 20, that is, the surface that the user of thecontrol stick 10 will contact to move the control stick 10. The convexend 22 will generally be a surface providing a good frictionalinterface. In the preferred embodiment, the convex end 22 is a sealed,smooth, easily cleaned surface, such as a closed cell skin formed on apolyurethane foam. The resiliency of the cushion 20 permits the cushion20 to be deformed and still provide excellent friction, even when thesurface thereof is smooth. However, if desired, the surface of theconvex end 22 may be textured or knurled. The second end 24 of thecushion 20 will be attached to the outer surface 19 of the cap 18 on thecontrol stick 10. In the preferred embodiment, a suitable adhesive isused to attach the cushion 20 to the outer surface 19 of the cap 18.

FIG. 5 is a sectional view of a second embodiment of the cushion of thisinvention, indicated generally at 30. The cushion 30 is generallycylindrical and includes a convex end 32, and a relatively flat end 33opposite the end 32. Although in the illustrated embodiment the end 32is convex, the end 32 may be formed to any suitable shape, such as aflat or a concave surface, as may the end 22 of the cushion 20.

A recess 34 is defined in the cushion 30, which generally conforms tothe outer surface of the end 21 of the control stick 10. For example, asshown in FIG. 6, the recess 34 may have a square perimeter, if the end21 of the control stick 10 is square in cross-section. The control stick10 extends into the recess 34. Preferably, to install the cushion 30onto the control stick 10, a suitable adhesive is applied to the upperend 21 of the control stick, to the interior surface of the recess 34 inthe cushion 30, or to both the upper end 21 of the control stick and tothe interior surface of the recess 34 in the cushion 30. The cushion 30is placed on the end 21 of the control stick 10 so that the cushion 30adheres to the end 21 of the control stick 10. Of course, the cushion 30could also be affixed to the control stick 10 by a resilient fit betweenthe recess 34 of the cushion 30 and the end 21 of the control stick 10.The cushion 30 is comprised of a soft material to permit use for anextended period of time without causing irritation to the finger tissue.

It may be desirable to manufacture the cushion 30 with portions havingdifferent levels of hardness. For example, the convex end 32 could besofter than the area of the cushion 30 surrounding the recess 34. Theharder area surrounding the recess 34 would assist in retaining thecushion 30 on the control stick 10 by maintaining its form, while theconvex end 32 of the cushion could be relatively soft.

One method of manufacturing the cushion 30 with portions havingdifferent levels of hardness would involve simultaneously injecting twoseparate types of material simultaneously into a cavity of single moldto form the cushion 30. For example, a first material having relativelysoft properties would be injected in the mold at the area where theconvex end 32 is formed, and a second material which is harder than thefirst material would be injected in the mold at the area where therecess 34 is formed. Accelerating agents, compatabilizing agents,fillers, mold release agents, and coloring agents can be introduced aswell, as will be appreciated by those skilled in the art. Somewherebetween the two ends 32 and 33, the first and second materials come intocontact and become affixed to one another. The cushion 30 would,therefore, be a single structure formed from two different materials,having different hardness characteristics when set or cured. For thepurposes of the present invention, curing can be accomplished by usingany suitable methods of solidifying or hardening a material, such as forexample, by adding or removing heat, inducing a catalytic reaction, orcontainment for a period of time to allow hardening to occur.

Another method of manufacturing the cushion 30 having multiple areaswith different levels of hardness would be to form the cushion 30 from asingle material, but altering the setting or formation of the materialso that the different areas have different hardness characteristics.This alteration of the formation process can be accomplished by varyingthe temperature gradient surrounding the mold, creating miniature airpockets within selected portions of the material, or by any othersuitable manufacturing process.

As an alternate embodiment, it is contemplated that a cushion of theinvention could be formed to completely encompass the cap 18 shown inFIGS. 2 and 3, except where the shaft of the control stick 10 extendsoutwardly therefrom. Such a cushion would have a cavity therein whichincludes a flange of material about an opening into the cavity. Such aflange of material would restrict the size of the opening into thecavity to a diameter which is less than the diameter of the cap 18, andthus retain the cushion on the cap 18, either alone or in combinationwith a suitable adhesive. The opening into such a cushion could beresiliently expanded to slip the cushion onto the cap 18 duringassembly, or when the cushion is replaced.

Although the preferred embodiment of the cushion 20 or 30 is for use ona portable notebook computer 14, it is envisioned that the cushion 20 or30 could be used on any keyboard or in any convenient location on anyinstrument requiring a control stick-like movement.

It is contemplated that the cushions 20 or 30 of the present inventioncan be sold separately from a notebook-type portable computer asreplacements or substitutes to the original control stick and capconfiguration. The cushions 20 or 30 can be sold in a kit form whichpreferably includes the necessary materials to affix the cushions 20 or30 to a control stick of a computer. The kit may include a plurality ofcushions 20 or 30 and a suitable adhesive material, such as a containerof contact cement or a pressure sensitive self-adhesive strip which ispre-applied to the cushions 20 or 30. For example, if contact cement issupplied with the kit, the user simply applies a coating of contactcement to either the originally supplied cap 18 or the end 21 of thecontrol stick 10, depending on the type of cushion 20 or 30 used. Acoating of contact cement is also applied to the cushion 20 or 30. Thecoatings of contact cement are then allowed to dry. The cushion 20 or 30is then pressed against the coated portion of the original cap 18 orcontrol stick 10, thereby affixing the cushion 20 or 30 to the controlstick 10.

FIG. 7 is a flow diagram of a method of forming a cushioned control 25stick according to the invention. The method of forming a cushionedcontrol stick may be summarized as follows: In a first step 100, acursor pointing device (control stick) with a cap having a firsthardness is provided. In a second step 200, a soft cushion is providedwhich has an outer surface of a second hardness which is less than thefirst hardness of the cap (i.e., the cushion is softer than the cap). Ina third step 300, the soft cushion is affixed to the relatively hardercap.

In summary, this invention includes:

A control stick with a contact surface which is relatively soft andnon-irritating to the body tissue of a user.

A cushion for a control stick, the cushion being softer than the controlstick.

A control stick cushion which can contact a display screen of a computerdisplay, deform elastically, and not damage the display screen.

A cap for a control stick, joy stick, or similar device which is softand non-irritating to the body tissue of a user during extended periodsof normal use.

In accordance with the provisions of the patent statutes, the principleand mode of operation of this invention have been explained andillustrated in its preferred embodiment. However, it must be understoodthat this invention may be practiced otherwise than as specificallyexplained and illustrated without departing from its spirit or scope.

What is claimed is:
 1. A cushion for a control stick of a computer,wherein said cushion has a first end and a second end, said first end ofsaid cushion defining a recess in said cushion, said recess being sizedto accommodate at least a portion of said control stick therein, andsaid second end of said cushion being formed of a soft material which issufficiently soft to prevent damage to a computer display screen whensaid second end is compressed thereagainst.
 2. The cushion of claim 1,wherein said soft material is selected from the group consisting of softrubber, soft foam, and polyurethane foam.
 3. The cushion of claim 1,wherein the control stick has a cap attached thereto, and said cushionis affixed to said cap.
 4. The cushion of claim 1, wherein said cushionhas a hardness which requires a force of less than about 10 gramsexerted on a probe having a contact surface area of about 1 squaremillimeter to deflect the surface of said cushion a distance of about0.25 millimeter.
 5. The cushion of claim 4, wherein said cushion has ahardness which requires a force of less than about 5 grams exerted on aprobe having a contact surface area of about 1 square millimeter todeflect the surface of said cushion a distance of about 0.25 millimeter.6. The cushion of claim 1, wherein said first end includes a portionwhich defines said recess and is formed of a material which is harderthan said soft material.
 7. The cushion of claim 1, wherein said softmaterial has a closed cell skin.
 8. The cushion of claim 1, wherein saidcushion defines a flange of material formed about said recess.
 9. Acursor pointing device for a computer comprising:a housing; a controlstick having an upper end and a lower end, said lower end attached tosaid housing; a cap attached to and enclosing said upper end of saidcontrol stick, said cap having an outer surface; and a cushion attachedto said outer surface of said cap, said cushion being formed of a softmaterial which is sufficiently soft to prevent damage to a computerdisplay screen when said cushion is compressed thereagainst.
 10. Thecursor pointing device of claim 9, wherein said soft material isselected from the group consisting of soft rubber, soft foam, andpolyurethane foam.
 11. The cushion of claim 9, wherein said cushion hasa hardness which requires a force of less than about 10 grams exerted ona probe having a contact surface area of about 1 square millimeter todeflect the surface of said cushion a distance of about 0.25 millimeter.12. The cushion of claim 9, wherein said cushion has a hardness whichrequires a force of less than about 5 grams exerted on a probe having acontact surface area of about 1 square millimeter to deflect the surfaceof said cushion a distance of about 0.25 millimeter.
 13. The cursorpointing device of claim 9, wherein said cushion defines a cavitytherein and an opening into said cavity, said cap being disposed in saidcavity, said cushion including a flange of material about said openingwhich releasably retains said cap in said cavity.
 14. The cursorpointing device of claim 9, wherein said cushion has a closed cell skin.15. The cursor pointing device of claim 9, wherein said cap is formed ofa material that is harder than said cushion.
 16. The cursor pointingdevice of claim 9 wherein said cushion is formed with a first convex endand a second concave end.
 17. A kit comprising:a cushion adapted to beattached to a control stick of a computer, said cushion being formed ofa soft material which is sufficiently soft to prevent damage to acomputer display screen when said cushion is compressed thereagainst;and an adhesive material for fastening said cushion to the controlstick.
 18. The kit of claim 17 in which said adhesive material iscontact cement contained in a container.
 19. The kit of claim 17,wherein said soft material is selected from the group consisting of softrubber, soft foam, and polyurethane foam.
 20. The kit of claim 17,wherein said cushion has a hardness which requires a force of less thanabout 10 grams exerted on a probe having a contact surface area of about1 square millimeter to deflect the surface of said cushion a distance ofabout 0.25 millimeter.
 21. The kit of claim 17, wherein said adhesivematerial comprises a pressure sensitive adhesive strip fixed to saidcushion.
 22. The kit of claim 17, wherein said cushion has a closed cellskin.
 23. The kit of claim 17 wherein said cushion is formed with afirst convex end and a second concave end.